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Message-ID: <1346938791.18408.7.camel@twins>
Date: Thu, 06 Sep 2012 15:39:51 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
dipankar@...ibm.com, akpm@...ux-foundation.org,
mathieu.desnoyers@...ymtl.ca, josh@...htriplett.org,
niv@...ibm.com, tglx@...utronix.de, rostedt@...dmis.org,
Valdis.Kletnieks@...edu, dhowells@...hat.com,
eric.dumazet@...il.com, darren@...art.com, fweisbec@...il.com,
sbw@....edu, patches@...aro.org
Subject: Re: [PATCH tip/core/rcu 06/23] rcu: Break up rcu_gp_kthread() into
subfunctions
On Thu, 2012-08-30 at 11:18 -0700, Paul E. McKenney wrote:
> +static int rcu_gp_kthread(void *arg)
> +{
> + struct rcu_state *rsp = arg;
> + struct rcu_node *rnp = rcu_get_root(rsp);
> +
> + for (;;) {
> +
> + /* Handle grace-period start. */
> + for (;;) {
> + wait_event_interruptible(rsp->gp_wq, rsp->gp_flags);
> + if (rsp->gp_flags && rcu_gp_init(rsp))
> + break;
> + cond_resched();
> + flush_signals(current);
> + }
>
> /* Handle grace-period end. */
> for (;;) {
> wait_event_interruptible(rsp->gp_wq,
> !ACCESS_ONCE(rnp->qsmask) &&
> !rcu_preempt_blocked_readers_cgp(rnp));
> if (!ACCESS_ONCE(rnp->qsmask) &&
> + !rcu_preempt_blocked_readers_cgp(rnp) &&
> + rcu_gp_cleanup(rsp))
> break;
> + cond_resched();
> flush_signals(current);
> }
> }
> return 0;
> }
Should there not be a kthread_stop() / kthread_park() call somewhere in
there?
Also, it could be me, but all those nested for (;;) loops make the flow
rather non-obvious.
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